Melanin is important for protecting human skin from damage induced by radiation. The accumulation of melanin in human skin cells can result in pigmentation disorders, such as melasma, freckles, ephelides, and senile lentigines, also referred to as liver spots or age spots. Aging and exposure to ultraviolet radiation from the sun can increase the occurrence of these and other types of pigmentation disorders.
Melanin is produced in a specialized group of cells known as melanocytes, which are located in the basal layer of the epidermis. Melanin production is controlled at least in part by tyrosinase enzymes and is produced by the oxidation of the amino acid tyrosine, followed by polymerization to produce the pigment melanin.
While melanin is useful in protecting human skin from sun damage, darkening of the skin as a result of melanin production can be aesthetically undesirable to some individuals. Skin lightening treatments and cosmetics are often used by individuals to reduce the appearance of pigmentation disorders, such as freckles or age spots. Conventional cosmetics only temporarily reduce the visibility of the undesirable pigmentation and can be inconvenient to use on a regular basis and on certain parts of the body.
Conventional skin lightening treatments can decrease the appearance of certain pigmentation disorders, but are often associated with undesirable side-effects. Hydroquinone is one example of a common skin lightener, however higher hydroquinone doses may require a prescription from a dermatologist. In some individuals, hydroquinone may cause undesirable discoloration of the skin. Arbutin is an example of a skin lightener that is derived from plants, such as mulberry, cranberry, bearberry and blueberry leaves. Arbutin is a glycosylated hydroquinone and thus may result in undesirable side effects that are similar to hydroquinone in some individuals.
While various efforts have been made, there remains an opportunity to provide additional methods and compositions for treating skin pigmentation disorders, particularly in lightening the appearance of dark spots on the skin and optionally preventing the formation of visible dark spots on the skin.